After 10 years your debt would have prescribed for sure. In order for the prescription to remain effective you must raise prescription as a defence. So when debt collectors phones you, simply say the debt has prescribed and then put the phone down. If they continue and persist, I would suggest that you quickly speak to an attorney to help you defend the case.
Soon there will be a new law prohibiting creditors or debt collectors from collecting debt that has prescribed. Until then, you have to raise prescription as a defence.
Do not pay anything or confirm anything in writing. If you confirm anything, it means you are acknowledging the debt and this constitutes an interruption of the prescription. In such case the collectors will be allowed to continue collection of the said debt.